Control apparatus



tzi-

Feb. 13, 1923.

A. H. CANDEE. coNTRoL APPARATUS.

immuun mtu 0m30.191s.

lie@

Ground INVENTOR A`TT0RNEY Andrew H Candee.

Normal Pas.

/sf Bra/fe Pos l 2nd Brake Pos.

VY" in..

LSI Rsi WITNESSES:

Patented Feb. 13, 1923.

f unir STAT E s PATENT- orarie-1;

ANDREW E. ommen, oF PITrsBUBGH, -PENNsYLvaNI-Agh'ssrcnon'rownsrfme- HOUSE 'ELEcrrBIc af. uANUFacTUnmG\comm,fA CORPORATION ceram-w =sYLvANm. a f i, l

eoN'rB/QLAPPABMQS. Appnanoa ineaociie'gaadwiafsxjimi.'Iaooaffiglepgoeiifaagust1a.?ieee." seiiarnoxssosem 'f Q wherein-tr glii's a ldigynmt'c `view-51H55 Be known-that IQ'ANP Y CAN'nEEfa th' miicirciiits of a systliniof 'ckiiitrolif-'to citizen lof the ,Uiitedjfstagtegand a resident Whichthe, present invention may be appli'eii: ot Pittsburgh,,in lihfGQi-lllly@1Q{Alltlghfly-l Figli'iS;Yiexiiil'partiallyin Vsection and 5 and `.Stat/e" of vlem'isylVania," 'llla've invented partiell' infelev'ation, of an 'apparatus co' afi/ieu; and use fu'l 'l'fmpip/'emntfin vControl strucd f tbfciirryout'- invention irr-eon-I 6o Appifatus, of fo'l owing isa speci- I1l`e :tio,ii `ithv ,a'fs'witifihing device; tlie'c'iiicuits fieati-on.: i., f L@ f l f y O fjyh'ill'farelillustra-ted inFig. l; andi.'I l My invention relates .to control apparatus f 3,is" a' yiew, 'inside'ele'vatim of a portio'of' and` particularly lto'wieinergency braking"v the 'apparatus that is illustrated in Fi'gf2.

means .,orl usein nn'e'ctin 'fwlth lelectricl Referring to Fig. lbf the drawing, 'the 65 railway/vehicles andthelike. f systerrshown 'comprises suitable supplycir` In the interests'ofgsafty,.Variouscheines cuit 'Conductors Trolleyhnd Ground a pii have been proposedin 4 the ast toproide ralityuof dynamo-electric machines respe'cf emergency braking lmeans?"Voir railway' vetively' having 'com nigutetor-type armatures hicles in case .the usual source of power A1 and A2 and field windings F1 and FQ'of '70 failed for any reason. For 'instunce, vatheamiliar seriestype, these machines beriousemergency brakingsystem's, dependent ind' mplloyedfor the usual purpose of proupon air pressure, haife been o'e'red in order pe ligafiailwa vehicle;'reversing switches tolallow the necessarybiaking effectin the 1 and 2,"preer ly` of a familiar-electricallycven'tot a failureof.'supplyeireuit voltage.,l controlled type, which may be mounted upon 75 However`4 .so ,far as I .am-aware.l -no systei'n" a ,single drum member; for reversing;V thir has ever been proposed for providingr :14n electrical 'relations of the armatures and ultimate Iandpracticallyr infallible einer? tield v windings undernormal conditions; an poney lu-aking'systein in cases there supplyaccelerating resistor 3; a"plurality ot circrcuit voltage andan' pressure both'iail. cilitladjusting switches LSJ Rl, R2, R3, R4, 80 One Vobject ofmy present'invention is to 5"., P and G au' auxiliary switching device or provide such an ultimate emergency; brakhralt'ing drum T, divided into two contacting system1 whereby the train operator may carrying ,portionst and 5, which is shown readilyl and reliably-brake'the vehicle both as having a normal position and three brake when .it is traveling in a forward direction positions;y and an electrically-controlled 85 and when it starts'A rolling backward. valve .meniher G for a purpose Eto he de- More specificallystated, it is one object scribed. f ol' my invention to provide means for brak- I'tvshonld he understood that the applicaing railway motors, without employing the tion of my invention is not restricted to the regular circuit-reversers orthe customarily particular control system herein illustrated1 90 employed auxiliary control apparatus,- by but may readily be employed in connection utilizin a controllable explosive action. with various other types of control systems,

Another object of my invention `istopro-f the vchief4 requisite being that either two 40 vide auxiliary control apparatus associated motors ora single motor and a suitable braku'ith an auxiliary Aswitching; device for inf ing circuit are employed under emergency 95 dcpcndently firing a series of cartridges to conditions for providingr a dj'namiobraking manipulate the switching device to succeseffect; i sive braking positions, to retard the vehicle l The .auxiliary switchiuLr device T. haringr movement in either directi0n. sections 4 :lud 5 that are associated with thc further object of my invention is to prorespective motors, preferably.' cmuprisesV a loo ride in connection with an emergency hralc single drum member of u familiar type and. ing system of the character just indicated. under normal running conditionsoccupies mire dependent upon the bnildingup of the illustrated position designated ns Non 5u rc machine voltages for preventingr thc sucmal Position for permit-ting the customary wessi-.e movements of the braking device electrical connections and circuit adjust4 105 c cr though another cartridge is red. ments that are employed in count-lion 'with )lv r-cntion may best he understood hy the familiar series-parallel control ot rail- ;ct'ercnpe to the accompanying drawing: way motors. Howcvcn when thc sYWHiH;

device is moved to its First Brake posinamely, the machinesre isdnnected from the suppl? circuit and are then connected in paralle relation, with the field windings reversed, therebyl causingthemadiines gto rovide the familiar dynamicbraking effect. ovement to the Second Brak bs'lt is employed to again reverse the field Wind-r in'gsr--and thus povde the'desiiebr'll'cln action in case-the vehicle a mpts to ro ture A2 and field windingl"2, as already pointed otfjand' conductor' 263m" Ground.

The `accelerating` resistor 3v` is fig-ain excluded from circuit, in accordance with familiar principles, toqaccelcrate vthe -motors to full-parallel xelation.

Assuming that 'the motorsigare running CA-vvitlrtiret-series connection and that, by reason of the failure of supply-circuit voltage l"or 'air"pre'ssure"fcr thc"usu:ilmechanical- 75 braking system, or to avoid accident, it is bcklifdljjf, desiredV to quickly"`brlre the vehicle, the

scribed?"l p A inasmuch .Sie thepfsiaelaf manifesti, talsythr that iste be employed Demon ivfch'whez'- illustre@ 1min. cintas miylbe readily fdevisgby those, skilled in the im, .Ihvef nef-iii: L, @meesterwshoiv 'siibhesj'stenl only sfliclelitl 'dei scription1 of thefixlitin-'ntil-'l 'system be given to vre'iitlei 'cles thef opijticnfof my present' inem-a are animieren thereof to' Va 'fzimllier" tjrpf sersparll'el railway-'nifbr CQhtfOl., v

Assuming mit tsjiesra-'tfeifct ateneration switches LS, R1',- andS arejinitielly closed to estblish a circuit` foin the .T'rollej' throufrh s w'itche's LS'nlrd RL the 'entire accelerating 'resistor Contact segment '10 of the auxiliary switchingfdevice' section '4, in its noiiniil 1position;conductors 11 ai1d`12, armature 'A1, reversing s'\i"itt.h" 1, conductor 13, contact'fsegment `-lelifof the svfithini,r dvice`4, (ieldwidi''g condl'lcto'r 15, contactsegment 1G ofthe auxiliary Vswitching device, conductorV 1f?. reversing switch 1, .-ondu'ctcns'4 18 and 19,- switch S, conductor 20, armature A2, reversing switch 2,' con ductor 21contact segment 22 ofthe auxillary switchingdevice section 5, field winding F2, conductor 23, contactpsegment 24 of the switching device, conductor 25, reversing,r switch 2,- and conductor 26 to the negative supply-circuit conductor Ground. The motors are thus connected 1n the familiar series reltion with the accelerating resistor 3;

To accelerate the In'achinesfto full-series relation. the resistor 3 is gradually excluded from circuit by means 'of the illustrated switches R1, R2, R3, and R4'in a familiar manner which need not be described in detail here.

The customary shunting transition 0f the motors to parallel relation is then effected h v opening the resistor-switches. closing switch l. ownin; r switch S and then clos`4 ing switch r. whereby the main circuit follows :wo hranchee from the conductor 1l. one o.' which includes conductor l2. the armature Al and the field winding F1. as |.-;i\;ifm l,\ traced. conductor 1S. switch G ami madurtor 2T to Ground. while the alluriifi'augh inclu-ics the switch i7, :irmaof, "the 'rllustated motors, the

auxiliary brakijz'eppuratus 7, comprisingr switching devices' 4 fand is ectutd'ito its First Brkef position 'in a nin'e'r to"80 i be de'scri'hed in de'tciljin connection' with Fig.f2,' whereby," in'the first: place, conductor 11 'breaks circuitfwith Contact member 10 to thereby disconnert the motors from 'the supply' circuit, an'd'condnctors 11, 3i "and 85 40 "then make connection with a c'ontzictV segment 30, while conductors 34 'and` 36 make connection with another 'contzict'isegmehtffl in the First Brake position. The function of contact'segments't) and 35 is -to 90 connect the niotorcii'cllits, each includingr an armature' and field windingin parallel relation. Conductor 11 isto-mectedv through conductor l2/to one terminal ofthe ari'n'ature Al, anilconfluctor Sli is committed to the corresponding terminal of the armature A2. The: other citls of 'the respective inntor circuits ronstitutil cnil-unters 1S- and 26, Whirh are resjectirelv connected 'tliiu'g'fh con'dnctoriiand through conductors 2T and 34 to Contact segmenti A further chngc of connections, nzun'clr. the reversal of the .field windings F1 and F2 with lespef-.tto the rox-respondingarmatures A1 and A2, is also effected byth'e above-mentioned actuation ot' the auxiliary .mfitclliugr apparatus to the First Brake position. Starting from the reversing switch 1, which, beingiuclep'cndent of'the auxiliaryv braking; drum T, does not have its circuit connections changed llj.' the actuation thereof, the new f 'i'riruit comprises conductor 13, Contact segment H8 offthc switchingrv device .4, conductor 15. field windin;r Fl, Contact segment 37. andi-ow i'lllctor li'. which connects will] thc revers ing switch l. Similar reversa! cf the held windingr F2 is :icrouxplishrd thrmuh the agency of contact segments 2li and 3? in the First Brake position c? switching de V30 Vive 5. comprising the second szfon of the ausiliari drum or cimugnr); lli-:tiring :1pparatus T.

.\s is well understood. the deconne-.tion

actristics 'of the "ti'ifof'rnacliines, caused slight' variations in the quality of iron in the Ymagnetic circuit,lenlcgtlrof air gap, etc., will :ausfe; the 'action vof'onebf "the niachnes to predoninat'e" Loyer that i :o ff the other', Vwhereby`- the' more' powerful Ii'nachit'le wzill act as af generator to forccurrent voltagein 'series with the ilmlore" nected across ,eachfinachue, l opens' or inet'a isiuimateriahA since, either''cs ise, the, desired,brakingeiectjvill bejscuijed.

If the machines are"t already', 'connected l' in arallel'relatior" by 'the closure? of switches i; andl :Gzwlien' theabove-xnentioncd 'einergency-braking' 'application' is'l made,' the same connections are ,.made, although, the switches' P and G' are'clos'll, contact segmentsi() and 35 of 'theauxiliaryy s viritchl` inlgdevice ,4 serve to parallel the switches. lnftbis way, it' is insured that'thedesired paralleling of'V thev motors be `-'effected even though, by reason of failure'of Vthean'xiliar vcontrol system, the switches and sbouldopen;

The above-described actions will serve to retard forward; 'movement of .the"vehicle when the motors are operating` either in 'se-` ries or i u parallel relation; owever, such v emergency action inigbtbe taken on a slight upward grade, which would cause the vebielv 4to roll backwardly soon as it had cometo rest since, ofcourse, dynamic-braking action ceases wbenthc rotative movement of tbc motor stops. To 'provide braki ng, under these conditions,E also, theeuXiliary switchingnpparatus 7 may bemroved to its- Second Brake position, which merely' restores the original field-winding connections on in otbervivords, again rerersestbem thus setting up'dynamic-brakingjcurri-.nts if tbc vehicle starts to roll backwardly, and elertively bringing the' vehicle to rest.

ltwwill be appreciated that any desired number of emergency braking positions may be provided upon the auxiliary switchinter apparatus by merely duplicating the first and the second braking positions.

i Reference may now bc had to Fig.`2 and Fig, Il which illustrate one form of emergcncy brakingr apparatus. whereby a movingvebiclc may be rapidly and reliably brought to rest. eren though supply-circuit voltage and air prcssure should concurrently fail.

The apparatus. in `'eneral. comprises a piston-and-crliudcr device 504 that is mechanically associated with the drum 7 carrying tbc auiliarv switching devices 4 and x to citer-t roaivc movement thereof to its successive braking psiti'ns, as desired a pressure-chamber devicel, which' isutllidifr'fsringfluid pressure created by Iuchanlsii; 52"3" auld a `manual controlling or catell 'adja'enttofthe "usual, controlapparatsf'inthef`ab or pri the platformfof the im? u l or rod to operate Within-fa suitablefencasing 'fneansor cylinder A 6'?"7 while, f 'upon thefther'" el'dfof the` piston "stein "65, is miilite'da plate' lf bearingupon a'helical s'p'rii'gl'68, which thusnormally biases the pistn" A'GlapthI therefo1e,"'the auxiliar;v switchiiigdruiil '7 tlothevillustrated normal position.

pipe br'passage 69 effects communicationbetveenthe piston end of the cylinder 67 a'ildtl'ie" valvey member`6, wl1ich is of a familiar type having'a normally open passage for permitting' communication between the pipe '69 and a second pipe 70 that enters the pressum-chgunleefr ldevice 51. The' functioii oflihre valve member '6"is to interrupt communication between the pipes'69 and 70 Whenever the actuatingleoil 41 is energized lojpreiient movement of tbe fluid-pressure actuatingr means 50 fora purpose to be set forth.' l f pressure-chamber device .":1 comprises a receptacle 7 5 having relatively tbickwalls to twithstand heavy fluid pressure, which enclo'sfe'th'e Ypregur'e cb'amber proper 76, with whieb@communicate a 4plurality of firingr passages 77,178' and'79V and aivcnt onoutlot S() ofll'elatirelysmal'l diameter. The. firing! passagesI 77` 78 and 7 9 are shaped to bold 1 a plurality of blank cart-ridges 81, 82 and 83 ofV affam'iliar type, the upper ends of which, comprisinrr the percussion caps. are covered by a suitably secured plate S4; bavin'jg'a pluralitv of openinifs or passages m"Y narrow =iliameter respectivcbv located rlirectli' yabove the pcrcussive wutcrs of tbe cartridge caps.

A pluralit)7 of firingr pins 85. 8G and S7 project downwardly into the passages just mentioned and are held just out of contact with theI permissive ccntcrs of the blank cartridges bv means of suitable helical s ins.` as illustrated.

The tiringY mechanism 52 comprises a pluralit)y of hammers 9(l 9i and 92. which located opposite tbe respective tiringr pins S5. QG and ST, and are biased to a downwardly- T ,1 has a ratchet ist mallyconstrained to their illustrated up'-4 extending tiring position-by means of helical springs 94, 95 and 96 that are secured to a supporti-ngrod 93 upon-which the hammers are loosely mounted. The hammers are norright positions, in opposition to the action of the' biasing. snr'rngs 942 95 and 96, through the agency of -alring rod 97 haxn'ngasaw tooth upper edge, or the equivalent; for

r meshing. with =a co-Operating saw-tooth, .disk

orgear member 98 to whichA is secured :a ratchet member99. A push-pin or'rod 100 normally engages the uppermostnotch of the retchetgmember 99, the pin being suitably` supported by any convenient stationaryA portion 102.026 the ear frame or of thecontrol apparatus-normally presentzin the vehicle I I D M d. such vaction, u fhi'lifvv'oul'd immediately-elimiand terminating in a suitable springs-.pr push-button 101.

Assuming that` the' emergency conditions have arisen` makingit necessary to employ-the auxiliary oremerg.- ency braking drum, the train operator `merely presses the push-button 101- to rotate gear member 98 through a eertainaangle corresponding to the distance between the tecthilofthe ratchet member. In this Way, the -fring rod 97 .is Withdrawnv from' in! frontof the firing hammer 90, which is thereupon actuated by the biasing spring 9i to strike the tiring pin S and discharge `the blank rartridge 'S1 throughthe firing passage 77 'no the. pressure chamber 7G. Since the valve-means is normallyr open, fluid pressure. thus produced is transmitted through pipe TO, valve and pipe (39 to the cylinder (ST of the (luid-actuating means 50. The piston ('16 is thus depressed, in opposition to the action of the spring 68, whereby the paivl rod (S2 is rotatively movedabout its pivotalpoint- 63 to'e'ause the pau/'161 to move upwardly and carry thev ratchet member and the associated auxiliary braking drum 7 through an angle corresponding to the distance between the teeth of the ratchet member, that is, to the First Brake position'. as illustrated in Fig. l.

'lhe piston 66 is slowly returned to its illustrated upper position by the spring 68 after the actuation just described` by reason of the gradual exhaust of the fluid pressure from the cylinder G7 through the pipes 39 and 70 and the vent or outlet 80 of the pressure chamber. whereby the piston and the pawtin a short time. reassuniethe illus trated -nornial positions in readiness for the next movement of the auxiliar)` braking drinn.A as about to be described.

in the event that. after the vehicle, has been brought lo rest. it tends to drift back .re-rdly. the push-liutton 10i nia \l be again guessed to permit the operation of the sce ond tiring hanuner 9l liu the Withdrawal oi the tiring rod 9T and thus explode cartridge above mentioned vthe ratchet memben99 and the associated.

82,;to ragain aetuatelthe piston-andcylinder mechanism 50`f`and`the emergency braking diiuin', ivhiclristhis time halted in its Secondl Brakepositin. Such action again revciusles'the field f windings, as previously pointed outto eifect dynamic braking durinothe backward movement vof the vehicle.

'.t ,Will be fapprecited" that, in case the momentum-driven',machines build up their brakinvfvoltagefto alsuitable'de ree, it is not dsiifab e-tofgfii'thr ctate t e auxiliary brakingfdiiumgffdr eialmple th'e train operator, jin a moment @of excitement, might again l press 1 the push-button 101.,I 'thinking toybtain `further bralng' etfect, when already'thefiillq'braking Yell'ort of' the ma chinesdiras.bfeing.. exertedr To .prevent any nate the braking' Q th'efvehiclthe valve means'gvsith its actuating coil 41, is provided. mi

W'heii tl1e"auxli'ay` braking drum is actuftefdto its ffFirstlBrake."position, in additionfto the Ycircuits previously traced in connection -withFigL 1, an auxiliary circuit, incliidfiiigcnductor 4`10,` is connected .to the contact-xne1nber30 of the braking drum. This' auxiliary circuitis continued from conductor 40. through the actuating coil 41 .and

conductor-'42, toA the negative conductor, l

or74 in other words, the actuating coil 4-1 is connected directly4 across the momentumdrrven machines. ConsequentlyJ upon the attainment of predetermined braking-voltage conditions, the actuating coil l1 is energized sufficiently to close the valve member and thus interrupt communication between the pipes (39A and TO. Under these circumstances i{thelpluelbbutton 101 is again accidentally onzotherwise pressed, even though a cartridge is fired, no movement of the auxiliary braking drum will oceur, but the explosive pressure will be gradually dissipated through the vent 80.

Itwillbe seen that Ihave thusl provided an ultimate emergency braking system that is not! dependent upon supply-circuit voltage. braking-system air pressure or any action lofthe'regular control system, but1 under any emergency conditions, braking oflthc vehicle in either a forward or a reverse direction muy be effected. as desired. Noreorergin case the lirst cartridge fails to eupiodeit is merely necessary to lire the. second and third with a short time interval therebetween to permit the pressure caused b v the firing of'the second cartridge to be dissipated, whereupon the piston (3G reassunies its normal upper position. rl`he firin;r oi' the third cartridge will then urinate the auxiliar)v braking drinn o its L"Third llralcc" position. which is equivalent to the LFirst Brake" position and thus ill ellect the desired braking action. The valve meansv (i will not operate upon the firingr of los llO

the aber mentioned second cartridge, since 4'the braking`-voltage willfrn'ot build upwith 4the'f'eld vwindings connectedl in the manner was.

I do not ni'slr'fto be restricted to thespecie-circuit. lconnections oi' arrangement-of mechanical parts` "hereinf illustrated, since it is evident =thatanv' desired-'number -of "cartridges," or J I'the etfufiyalent, 'and -correspending emergono `)braking positions: may 'be utilized. 1I d ire*.,therefore,f1tha,tonly such limitationslshallbeimposed as areindictated in 'theappendedsclaiiis.i1 v 15M 15Thefconibination'zfwithi azrotatablej contact-'carrying rmemberttorfcbntr'ollmg. =an

I lclaim'jas my-irivention:'"11- electrical bralringf"system-,1 foi.Y fa fpistonandcylinder device mechanicallyfjl connected thereto, and explosive'meanshfor effecting f the vactuation-of said 'piston-'and said rotatable member to a braking position under predetermined, conditions.

-Qf The combiationsfwith a multi-positioirmember, of explosive means for actuatingsf said member to its successive positions in a stepby-step manner.

3. The combination with a rotatable control member. ot' explosive means for intermittently actuating said member under predetermined conditions.

1. The combination with a multi-position member and actuating means therefor, of a pressure chamber communicating with said actuating means. a cartridge located in firimcr communication with said chamber. and means for firing said cartridge to effect the movement of said member from one position to another.

5. The combination with a multi-position rotatable contaetcarrying r member and fluid-pressure actuating means therefor. of a pressure chamber communicatingr with said actuating means, aplurality of' cartridges located in firing communication with said pressure chamber, and means for suc cessively firing said cartridges to e'ect a step-by-step movement of said rotatable member.

(l. Tn a control system. thc combination with a plurality of dynamo-electric machines severally having; armatures and field windings. of a switching device having emergency means for effecting electrical braking` connections of the machines. and means dependent upon an explosive action for rendering Said emergency means active.

T. In a control system. the combination with a plurality of dynau'io-electric machines severally having armatures and field windings. of a rotatable switchingdevice having.r an emergency position for parallelinf the machines and reversing the electrical relations of the armatures and field windings, explosive means, and means for applyiur! the explosive force thereof to more said switching device into said emergency position. 4`.8. In a control system, the combination with a plurality of dynamoelcctric machines severally having armatures and field fwindings, of. a rotatable switching device havingr a. plurality of emergency positions for parallelin;r the 'machines and for sucocssivelyreversing the electrical relations of 'f` the'armatures4 and fieldwindjngs. and explosive means-for Vint'erinittently actuating saidsvr'itchinpr device to its successivo emercencyrpositions. A ".-J9. In Lacontrotsystem, the combination @Witha lplurality of dynamo-electric mai Ichines'severally .having armatures and field l lwindingsfgf ofwa rotatable switching dev-ice 1 hairing?'an'iernerggencj.yr position for parallel ing the machines and reversingr the electri- -calrelationsof the armatures and field ,windingsactuating means for said switching devioe.la :pressure chamber communicat- "insr withsaid-actuatingmeans. a cartridge located in firing communica-tion with said chamber. and means for firingr said cartridge to effect the movement of said switchingr device to said emergency position.

l0. In a control system.y the combination with a supply circuit and a plurality of dynanio-electric machin'es severally having armatures and Held windings, of a rotatablev switching device having :i plurality of emergency positions for parallcling the machines and for successively reversing the electrical relations of the armatures and field windings and tor disconnecting thcmachines from said supply circuit. fluidpressure actuatingr means for said switchimT device. a. pressure chamber communicatinrr with said actuating` means. a plurality of cartridges located in firing conmnunication with said pressure chamber. and means for successively rinp; said cartridges to effect :i step-b v-stcp movement of said suifcliinsf device to the. successive emergency positions.

ll. In a control system. the combination with a supply circuit and a. plurality of dyname-electric machines sevcrf\ll \v harinar ari matures and field windings. ot means for normallyreversing thc electrical relations nf' the armatures 71nd field windings, .'i, Switching device indcpcnden of said revers ing means and having an emergency position for disconnecting the machines from thc supply circuit :and narallcling the nur fbiucs and rcvcrsinrr said electrical relations. and means independent. of thc con trol system for actuatinc` said switching dcvice to its emergency position.

lf2. ln a control system. thc, combina tion with :1 pluralitiv of dynamo-electric machines severally havin;T armatures and field windings` of a switching device having plural emergency means for effecting eleclrical braking connections of the machines, explosive .means for rendering one of said. emergency means active, and means for preventing the use of another emergencyY means if predetermined braking conditions obtain in the machine circuits.

13. Ina control system, the combination, with a plurality of dynamo-electric ma-- chines severally having armatures and field windings, of a rotatable switching device-` having a plurality of emergency'positionse for parallelintgr the machines and for successively reversing the electrical relations ofthe armatures and field windings, explosive means for intern'iittently lactuating said switching device to its successive positions under predeterminedconditions, and means .Y for preventing more than one actuationififthe machine voltages reacha predeterminedi value.

14. In a control system1 the combinationwith a plurality of dynamo-electric Ina-f chines severally having'iarmatures and field windings, of a rotatable switching device haivingia plurality,offeinergency posi tions for paralleling theniachines. and for successively reversing` the. electrical relations of -thearinatufres and field-windings, fluid-pressure actuating means for said switching device, a pressure chamber communicating. with said actuating means, a plurality -of cartridges located in firingrr eommunicationnvith said pressure chamber, xneansf for successively firingfsaid vcartridges to eifect a^.stepby-step=.movement of said switching. device to the successive emergene)- .positions under predetermined conditions, normally-open valve means located interinediate said .pressure chamber .and fsaicl actuatingl` means,v and an actuating coil en ergizedm-c1osesaidvalve means upon the attainmentcf predeterm ined voltage vconditions'vin said f machines.

In: testimonyfmhereof, I have hereunto subscribed `myflname zthis 26th day of Oct. 1918.

ANDREW-H. CANDEE. 

